Field of the Invention
The present invention relates to a biometric recognition apparatus, especially to a biometric recognition apparatus with reflection-shielding electrode.
Description of Prior Art
Biometric recognition technology has been widely applied to personal identification and authentication. The conventional biometric recognition technologies can be classified into fingerprint recognition, iris recognition or DNA recognition and so on. Due to safety, non-invasiveness and efficiency considerations, fingerprint recognition becomes main stream technology. The fingerprint recognition device can scan fingerprint image by optical scanning, thermal imaging, supersonic imaging or capacitive imaging. For compactness, cost, power-saving, reliability and security concerns, the capacitive fingerprint sensor becomes popular for biometric recognition technology applied to portable electronic devices.
The conventional capacitive fingerprint sensors can be classified into swipe type and area type (pressing type), and the area type has better identification correctness, efficiency and convenience. However, the area type capacitive fingerprint sensor generally integrates the sensing electrodes and the sensing circuit into one integrated circuit (IC) protected by a sapphire film with thickness below 100 um because the sensed signals are minute and the background noise is huge in comparison with the minute sensed signals. As a result, the material cost and package cost is high and the product lifetime and durability are influenced. It is a development trend to enhance the sensing ability and signal-to-noise ratio for the sensing circuit such that distance between the sensing electrode and user finger can be increased and the package of the sensing IC can be simplified. It is also desirable to integrate the sensing electrode to location below the protection glass or even more desirable to integrate the sensing electrode into the display panel, thus greatly reducing cost and enhancing product lifetime and durability.